That's similar to hydro-forming steel, which the automakers are starting to do more of as try and engineer the exact shape of things like body chassis and frame parts so as to maximize strength while minimizing weight and reducing the number of manufacturing operations.
Anybody here seen or done metal spinning? The wheels for our solar car's wheelmotors were originally to have been magnesium castings, but they were impossible to machine, so we switched to spun rims, and spun wheel discs. Cheap, strong, stiff and still in production, 25 years later.
Cheers
Greg Locock
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The method shown here is similar to the way some 2 stroke enthusiasts make tuned exhaust pipes. They weld two sections of flat steel or stainless together around the perimeter in the correct pattern, attach a tube fitting to one end, then inflate the part with a pressure washer or hydraulic pump.
I did some work for a local artsy-fartsy light fixture guy and stumbled past a guy doing metal spinning. They had two metal spinner machines. It was an "oh wow" moment.
I helped a guy produce some tubes (flattened with a taper and a bit of twist). He built a steel split die to control the outside shape and we filled them with water, plugged the ends, and provided a vent to a control valve set to hold 3,200psi, and squeezed them. Bingo, poor man's hydro form.
